Seasonal Variation and Health Risk Assessment of Polycyclic Aromatic Hydrocarbons in Miaoli City, Taiwan

Abstract

The ambient PAHs levels in the downtown area of a traditional small city were analyzed for winter and summer seasons. A total of 16 PAHs in gaseous and particulate phase were quantified. The average gaseous PAHs were 2,189 ± 1,194 and 623.8 ± 545.1 ng/m(3) in winter and summer seasons, respectively. For the PAHs in particulate phase, they were 40.32 ± 12.15 and 11.99 ± 5.63 ng/m(3) in winter and summer seasons, respectively. These values were comparable to those reported for large cities or even higher. The estimated BaPeq was 12.32 ± 6.34 ng/m(3). As low-molecular-weight PAHs primarily existed in gaseous phase, high-molecular-weight PAHs in particulate phase became a significant fraction of total particulate phase PAHs. Particulate phase PAHs was significantly inversely associated with the ambient temperature for each individual PAHs species. However, this relationship did not exist for high-molecular-weight PAHs in gaseous phase. The results indicated the photo-degradation of high-molecular-weight PAHs should warrant a further thoughtfully investigation.